Liquid crystal composition and liquid crystal display device

ABSTRACT

A liquid crystal composition has a negative dielectric anisotropy, and contains a specific bicyclic compound having a large optical anisotropy and a small viscosity as a first component and a specific compound having a large maximum temperature and a large dielectric anisotropy as a second component, and may contain a specific compound having a small viscosity as a third component, a specific compound having a large dielectric anisotropy as a fourth component and a specific compound having a large dielectric anisotropy as a fifth component, and a liquid crystal display device includes the composition.

TECHNICAL FIELD

The invention relates to a liquid crystal composition mainly suitablefor use in an active matrix (AM) device and so forth, and an AM deviceand so forth including the composition. In particular, the inventionrelates to a liquid crystal composition having a negative dielectricanisotropy, and a device that includes the composition and has a modesuch as an in-plane switching (IPS) mode, a vertical alignment (VA)mode, a fringe field switching (FFS) mode or a polymer sustainedalignment (PSA) mode, and so forth.

BACKGROUND ART

In a liquid crystal display device, a classification based on anoperating mode for liquid crystals includes a phase change (PC) mode, atwisted nematic (TN) mode, a super twisted nematic (STN) mode, anelectrically controlled birefringence (ECB) mode, an opticallycompensated bend (OCB) mode, an in-plane switching (IPS) mode, avertical alignment (VA) mode, a fringe field switching (FFS) mode and apolymer sustained alignment (PSA) mode. A classification based on adriving mode in the device includes a passive matrix (PM) and an activematrix (AM). The PM is classified into static, multiplex and so forth,and the AM is classified into a thin film transistor (TFT), a metalinsulator metal (MIM) and so forth. The TFT is further classified intoamorphous silicon and polycrystal silicon. The latter is classified intoa high temperature type and a low temperature type according to aproduction process. A classification based on a light source includes areflective type utilizing natural light, a transmissive type utilizingbacklight and a transflective type utilizing both the natural light andthe backlight.

The devices include a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to obtainan AM device having good general characteristics. Table 1 belowsummarizes a relationship of the general characteristics between twoaspects. The general characteristics of the composition will be furtherexplained based on a commercially available AM device. A temperaturerange of the nematic phase relates to a temperature range in which thedevice can be used. A preferred maximum temperature of the nematic phaseis about 70° C. or higher and a preferred minimum temperature of thenematic phase is about −10° C. or lower. Viscosity of the compositionrelates to a response time in the device. A short response time ispreferred for displaying moving images on the device. Accordingly, asmall viscosity in the composition is preferred. A small viscosity at alow temperature is further preferred.

TABLE 1 General Characteristics of Composition and AM Device GeneralCharacteristics General Characteristics No. of Composition of AM Device1 Wide temperature range of a nematic Wide usable temperature rangephase 2 Small viscosity ¹⁾ Short response time 3 Suitable opticalanisotropy Large contrast ratio 4 Large positive or negative dielectricLow threshold voltage and anisotropy small electric power consumptionLarge contrast ratio 5 Large specific resistance Large voltage holdingratio and large contrast ratio 6 High stability to ultraviolet Longservice life light and heat ¹⁾ A liquid crystal composition can beinjected into a liquid crystal cell in a shorter period of time.

An optical anisotropy of the composition relates to a contrast ratio inthe device. A product (Δn×d) of the optical anisotropy (Δn) of thecomposition and a cell gap (d) in the device is designed so as tomaximize the contrast ratio. A suitable value of the product depends onthe type of the operating mode. The suitable value is in the range ofabout 0.30 micrometer to about 0.40 micrometer in a device having the VAmode, and in the range of about 0.20 micrometer to about 0.30 micrometerin a device having the IPS mode or the FFS mode. In the above case, acomposition having a large optical anisotropy is preferred for a devicehaving a small cell gap. A large absolute value of dielectric anisotropyin the composition contributes to a low threshold voltage, a smallelectric power consumption and a large contrast ratio in the device.Accordingly, the large absolute value of dielectric anisotropy ispreferred. A large specific resistance in the composition contributes toa large voltage holding ratio and a large contrast ratio in the device.Accordingly, a composition having a large specific resistance at roomtemperature and also at a high temperature in an initial stage ispreferred. A composition having a large specific resistance at roomtemperature and also at a high temperature even after the device hasbeen used for a long period of time is preferred. Stability of thecomposition to ultraviolet light and heat relates to a service life ofthe liquid crystal display device. In the case where the stability ishigh, the device has a long service life. Such characteristics arepreferred for an AM device for use in a liquid crystal projector, aliquid crystal television and so forth.

A composition having a positive dielectric anisotropy is used for an AMdevice having the TN mode. On the other hand, a composition having anegative dielectric anisotropy is used for an AM device having the VAmode. A composition having a positive or negative dielectric anisotropyis used for an AM device having the IPS mode or the FFS mode. Acomposition having a positive or negative dielectric anisotropy is usedfor an AM device having the PSA mode. Examples of the liquid crystalcomposition having the negative dielectric anisotropy are disclosed inPatent literature Nos. 1 to 4 as described below.

CITATION LIST Patent Literature

-   Patent literature No. 1: JP 2009-270026 A.-   Patent literature No. 2: WO 2007-108307 A.-   Patent literature No. 3: JP 2008-19425 A.-   Patent literature No. 4: JP 2008-505235 A.

A desirable AM device has characteristics such as a wide temperaturerange in which a device can be used, a short response time, a largecontrast ratio, a low threshold voltage, a large voltage holding ratioand a long service life. A shorter response time even by one millisecondis desirable. Thus, desirable characteristics of a composition include ahigh maximum temperature of a nematic phase, a low minimum temperatureof the nematic phase, a small viscosity, a suitable optical anisotropy,a large positive or negative dielectric anisotropy, a large specificresistance, a high stability to ultraviolet light and a high stabilityto heat.

DISCLOSURE OF INVENTION Technical Problem

One of the aims of the invention is to provide a liquid crystalcomposition satisfying at least one of characteristics such as a highmaximum temperature of a nematic phase, a low minimum temperature of thenematic phase, a small viscosity, a suitable optical anisotropy, a largenegative dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light and a high stability to heat. Another aimis to provide a liquid crystal composition having a suitable balanceregarding at least two of the characteristics, in particular, a liquidcrystal composition satisfying a high maximum temperature, a largenegative dielectric anisotropy and a small viscosity. A further aim isto provide a liquid crystal display device including such a composition.An additional aim is to provide a composition having characteristicssuch as a suitable optical anisotropy to be a small optical anisotropyor a large optical anisotropy, a large negative dielectric anisotropyand a high stability to ultraviolet light, and is to provide an AMdevice having a short response time, a large voltage holding ratio, alarge contrast ratio, a long service life and so forth.

Solution to Problem

The invention concerns a liquid crystal composition that has a negativedielectric anisotropy and contains at least one compound selected fromthe group of compounds represented by formula (1) as a first componentand at least one compound selected from the group of compoundsrepresented by formula (2) as a second component, and a liquid crystaldisplay device including the composition:

wherein R¹ and R² are independently alkyl having 1 to 12 carbons; R³ andR⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; ring A is independently:

and in the rings, at least one of ring A is:

Z¹ is independently a single bond, ethylene or methyleneoxy; and m is 1or 2.

Advantageous Effects of Invention

An advantage of the invention is a liquid crystal composition satisfyingat least one of characteristics such as a high maximum temperature of anematic phase, a low minimum temperature of the nematic phase, a smallviscosity, a suitable optical anisotropy, a large negative dielectricanisotropy, a large specific resistance, a high stability to ultravioletlight, and a high stability to heat. One aspect of the invention is aliquid crystal composition having a suitable balance regarding at leasttwo of the characteristics. Another aspect is a liquid crystal displaydevice including such a composition. A further aspect is a compositionhaving a suitable optical anisotropy, a large negative dielectricanisotropy, a high stability to ultraviolet light and so forth, and anAM device having a short response time, a large voltage holding ratio, alarge contrast ratio, a long service life and so forth.

BEST MODE FOR CARRYING OUT THE INVENTION

Usage of terms herein is as described below. A liquid crystalcomposition or a liquid crystal display device according to theinvention may be occasionally abbreviated as “composition” or “device,”respectively. The liquid crystal display device is a generic term for aliquid crystal display panel and a liquid crystal display module.“Liquid crystal compound” means a compound having a liquid crystal phasesuch as a nematic phase or a smectic phase, or a compound having noliquid crystal phase but being useful as a component of the composition.Such a useful compound has a six-membered ring such as 1,4-cyclohexyleneand 1,4-phenylene, and a rod-like molecular structure. An opticallyactive compound and a polymerizable compound may be occasionally addedto the composition. Even in the case where the compounds are liquidcrystalline, the compounds are classified as an additive herein. Atleast one compound selected from the group of compounds represented byformula (1) may be occasionally abbreviated as “compound (1).” “Compound(1)” means one compound or two or more compounds represented by formula(1). A same rule applies to any other compound represented by any otherformula. A term “arbitrary” shows that not only positions but also thenumber can be freely selected, but does not include the case where thenumber is 0 (zero).

A higher limit of a temperature range of the nematic phase may beabbreviated as “maximum temperature.” A lower limit of the temperaturerange of the nematic phase may be abbreviated as “minimum temperature.”An expression “having a large specific resistance” means that thecomposition has a large specific resistance at room temperature and alsoat a temperature close to the maximum temperature of the nematic phasein an initial stage, and that the composition has a large specificresistance at room temperature and also at a temperature close to themaximum temperature of the nematic phase even after the device has beenused for a long period of time. An expression “having a large voltageholding ratio” means that the device has a large voltage holding ratioat room temperature and also at a high temperature in an initial stage,and that the device has a large voltage holding ratio at roomtemperature and also at a temperature close to the maximum temperatureof the nematic phase even after the device has been used for a longperiod of time. When characteristics such as an optical anisotropy areexplained, values obtained according to the measuring methods describedin Examples will be used. A first component includes one compound or twoor more compounds. “Ratio of the first component” is expressed in termsof weight percent (% by weight) of the first component based on thetotal weight of the liquid crystal composition. A ratio of a secondcomponent or the like is also expressed in a similar manner. A ratio ofthe additive mixed with the composition is expressed in terms of weightpercent (% by weight) or weight parts per million (ppm) based on thetotal weight of the liquid crystal composition.

A symbol R³ is used for a plurality of compounds in chemical formulas ofcomponent compounds. In two of arbitrary compounds among the pluralityof compounds, a group to be selected by R³ may be identical ordifferent. In one case, for example, R³ of compound (2) is ethyl and R³of compound (2-1) is ethyl. In another case, R³ of compound (2) is ethyland R³ of compound (2-1) is propyl. A same rule applies to a symbol R⁴,R⁵ or the like.

The invention includes the items described below.

Item 1. A liquid crystal composition that has a negative dielectricanisotropy and contains at least one compound selected from the group ofcompounds represented by formula (1) as a first component and at leastone compound selected from the group of compounds represented by formula(2) as a second component:

wherein R¹ and R² are independently alkyl having 1 to 12 carbons; R³ andR⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; ring A is independently:

and in the rings, at least one of ring A is:

Z¹ is independently a single bond, ethylene or methyleneoxy; and m is 1or 2.Item 2. The liquid crystal composition according to item 1, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-1) to formula (2-8):

wherein R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons.Item 3. The liquid crystal composition according to item 2, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-4).Item 4. The liquid crystal composition according to item 2, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-8).Item 5. The liquid crystal composition according to any one of items 1to 4, wherein a ratio of the first component is in the range of 5% byweight to 40% by weight, and a ratio of the second component is in therange of 5% by weight to 95% by weight, based on the total weight of theliquid crystal composition.Item 6. The liquid crystal composition according to any one of items 1to 5, further containing at least one compound selected from the groupof compounds represented by formula (3) as a third component:

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring B, ring C and ring D are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene; Z² andZ³ are independently a single bond, ethylene, methyleneoxy orcarbonyloxy; and n is 0, 1 or 2, and when n is 0, at least one of ring Cand ring D is 1,4-cyclohexylene.Item 7. The liquid crystal composition according to item 6, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1) to formula (3-12):

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.Item 8. The liquid crystal composition according to item 7, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1).Item 9. The liquid crystal composition according to item 7, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-7).Item 10. The liquid crystal composition according to any one of items 6to 9, wherein a ratio of the third component is in the range of 10% byweight to 90% by weight based on the total weight of the liquid crystalcomposition.Item 11. The liquid crystal composition according to any one of items 1to 10, further containing at least one compound selected from the groupof compounds represented by formula (4) as a fourth component:

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons; ring E andring F are independently 1,4-cyclohexylene or 1,4-phenylene; Z⁴ and Z⁵are independently a single bond, ethylene or methyleneoxy; X¹ and X² areindependently fluorine or chlorine; Y¹ is hydrogen or methyl; and p is1, 2 or 3, q is 0 or 1, and a sum of p and q is 1, 2 or 3.Item 12. The liquid crystal composition according to item 11, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-1) to formula (4-9):

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons.Item 13. The liquid crystal composition according to item 12, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-1).Item 14. The liquid crystal composition according to item 12, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-4).Item 15. The liquid crystal composition according to item 12, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-6).Item 16. The liquid crystal composition according to any one of items 11to 15, wherein a ratio of the fourth component is in the range of 5% byweight to 80% by weight based on the total weight of the liquid crystalcomposition.Item 17. The liquid crystal composition according to any one of items 1to 16, further containing at least one compound selected from the groupof compounds represented by formula (5) as a fifth component:

wherein R⁹ and R¹⁰ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; ring Gand ring I are independently 1,4-cyclohexylene or 1,4-phenylene; Z⁶ andZ⁷ are independently a single bond, ethylene, methyleneoxy orcarbonyloxy; and r is 0, 1 or 2, s is 0 or 1, and a sum of r and s is 1or 2.Item 18. The liquid crystal composition according to item 17,

wherein the fifth component is at least one compound selected from thegroup of compounds represented by formula (5-1) to formula (5-5):

wherein R⁹ and R¹⁹ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons.Item 19. The liquid crystal composition according to item 18, whereinthe fifth component is at least one compound selected from the group ofcompounds represented by formula (5-4).Item 20. The liquid crystal composition according to any one of items 17to 19, wherein a ratio of the fifth component is in the range of 5% byweight to 40% by weight based on the total weight of the liquid crystalcomposition.Item 21. The liquid crystal composition according to any one of items 1to 20, wherein a maximum temperature of a nematic phase is 70° C. orhigher, an optical anisotropy (25° C.) at a wavelength of 589 nanometersis 0.08 or more, and a dielectric anisotropy (25° C.) at a frequency of1 kHz is −2 or less.Item 22. A liquid crystal display device including the liquid crystalcomposition according to any one of items 1 to 21.Item 23. The liquid crystal display device according to item 22, whereinan operating mode in the liquid crystal display device is a VA mode, anIPS mode, a FFS mode or a PSA mode, and a driving mode in the liquidcrystal display device is an active matrix mode.Item 24. Use of a liquid crystal composition in the liquid crystaldisplay device according to any one of item 22 or 23.

The invention further includes the following items: (1) the composition,further containing the optically active compound; (2) the composition,further containing the additive such as an antioxidant, an ultravioletlight absorber or an antifoaming agent; (3) an AM device including thecomposition; (4) a device including the composition, and having a TN,ECB, OCB, IPS, FFS, VA or PSA mode; (5) a transmissive device includingthe composition; (6) use of the composition as the composition havingthe nematic phase; and (7) use as an optically active composition byadding the optically active compound to the composition.

The composition of the invention will be explained in the followingorder. First, a constitution of the component compounds in thecomposition will be explained. Second, main characteristics of thecomponent compounds and main effects of the compounds on the compositionwill be explained. Third, a combination of components in thecomposition, a preferred ratio of the component compounds and the basisthereof will be explained. Fourth, a preferred embodiment of thecomponent compounds will be explained. Fifth, specific examples of thecomponent compounds will be shown. Sixth, the additive that may be mixedwith the composition will be explained. Seventh, methods forsynthesizing the component compounds will be explained. Last, anapplication of the composition will be explained.

First, the constitution of the component compounds in the compositionwill be explained. The composition of the invention is classified intocomposition A and composition B. Composition A may further contain anyother liquid crystal compound, the additive, an impurity or the like, inaddition to the compound selected from compound (1), compound (2),compound (3), compound (4) and compound (5). “Any other liquid crystalcompound” means a liquid crystal compound different from compound (1),compound (2), compound (3), compound (4) and compound (5). Such acompound is mixed with the composition for the purpose of furtheradjusting the characteristics. Of any other liquid crystal compounds, aratio of a cyano compound is preferably as small as possible in view ofstability to heat or ultraviolet light. A further preferred ratio of thecyano compound is 0% by weight. The additive includes the opticallyactive compound, the antioxidant, the ultraviolet light absorber, a dye,the antifoaming agent, the polymerizable compound and a polymerizationinitiator. The impurity includes a compound mixed in a process such aspreparation of the component compounds. Even in the case where thecompound is liquid crystalline, the compound is classified as theimpurity herein.

Composition B consists essentially of compounds selected from compound(1), compound (2), compound (3), compound (4) and compound (5). A term“essentially” means that the composition does not contain any liquidcrystal compound different from the compounds, excluding the additiveand the impurity. Composition B has a smaller number of components thancomposition A has. Composition B is preferred to composition A in viewof cost reduction. Composition A is preferred to composition B in viewof possibility of further adjusting physical properties by mixing anyother liquid crystal compound.

Second, the main characteristics of the component compounds and the maineffects of the compounds on the characteristics of the composition willbe explained. The main characteristics of the component compounds aresummarized in Table 2 on the basis of advantageous effects of theinvention. In Table 2, a symbol L stands for “large” or “high,” a symbolM stands for “medium,” and a symbol S stands for “small” or “low.” Thesymbols L, M and S represent classification based on a qualitativecomparison among the component compounds, and 0 (zero) means “a value isnearly zero.”

TABLE 2 Characteristics of Compounds Compounds (1) (2) (3) (4) (5)Maximum temperature M M to L S to L M to L M Viscosity S M to L S to M Mto L L Optical anisotropy M to L M S to L M to L M to L Dielectricanisotropy 0 L 0 L L Specific resistance L L L L L

Upon mixing the component compounds with the composition, the maineffects of the component compounds on the characteristics of thecomposition are as described below. Compound (1) decreases the minimumtemperature, increases the optical anisotropy and decreases theviscosity. Compound (2) increases the absolute value of dielectricanisotropy, decreases the minimum temperature and decreases theviscosity. Compound (3) decreases the viscosity, adjusts the suitableoptical anisotropy and decreases the minimum temperature. Compound (4)increases the absolute value of dielectric anisotropy, decreases theminimum temperature and decreases the viscosity. Compound (5) increasesthe absolute value of dielectric anisotropy and decreases the minimumtemperature.

Third, the combination of components in the composition, the preferredratio of the component compounds and the basis thereof will beexplained. The combination of the components in the composition includesa combination of the first component and the second component, acombination of the first component, the second component and the thirdcomponent, a combination of the first component, the second componentand the fourth component, a combination of the first component, thesecond component and the fifth component, a combination of the firstcomponent, the second component, the third component and the fourthcomponent, a combination of the first component, the second component,the third component and the fifth component, a combination of the firstcomponent, the second component, the fourth component and the fifthcomponent, and a combination of the first component, the secondcomponent, the third component, the fourth component and the fifthcomponent.

A preferred combination of the components in the composition includesthe combination of the first component, the second component, the thirdcomponent and the fourth component for increasing the maximumtemperature or decreasing the viscosity, and the combination of thefirst component, the second component, the third component, the fourthcomponent and the fifth component for increasing the absolute value ofdielectric anisotropy, decreasing the viscosity or decreasing theminimum temperature.

A preferred ratio of the first component is about 5% by weight or morefor increasing the optical anisotropy and decreasing the viscosity, andabout 40% by weight or less for decreasing the minimum temperature. Afurther preferred ratio is in the range of about 10% by weight to about35% by weight. A particularly preferred ratio is in the range of about15% by weight to about 30% by weight.

A preferred ratio of the second component is about 5% by weight or morefor increasing the absolute value of dielectric anisotropy, and about95% by weight or less for decreasing the minimum temperature. A furtherpreferred ratio is in the range of about 10% by weight to about 70% byweight for decreasing the viscosity. A particularly preferred ratio isin the range of about 20% by weight to about 50% by weight.

A preferred ratio of the third component is about 10% by weight or morefor decreasing the viscosity, and about 90% by weight or less fordecreasing the minimum temperature. A further preferred ratio is in therange of about 20% by weight to about 80% by weight. A particularlypreferred ratio is in the range of about 30% by weight to about 70% byweight.

A preferred ratio of the fourth component is about 5% by weight or morefor increasing the absolute value of dielectric anisotropy, and about80% or less for decreasing the minimum temperature. A further preferredratio is in the range of about 15% by weight to about 70% by weight. Aparticularly preferred ratio is in the range of about 30% by weight toabout 60% by weight.

A preferred ratio of the fifth component is about 5% by weight or morefor increasing the absolute value of dielectric anisotropy, and about40% by weight or less for decreasing the minimum temperature. A furtherpreferred ratio is in the range of about 7% by weight to about 30% byweight. A particularly preferred ratio is in the range of about 10% byweight to about 20% by weight.

Fourth, the preferred embodiment of the component compounds will beexplained.

R¹ and R² are independently alkyl having 1 to 12 carbons, R³, R⁴, R⁷,R⁸, R⁹ and R¹⁰ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons, and R⁵ and R⁶are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine.

Preferred R¹ or R² is alkyl having 1 to 5 carbons for decreasing theminimum temperature. Further preferred R¹ or R² is alkyl having 1 to 3carbons for decreasing the viscosity. Preferred R³, R⁴, R⁷, R⁸, R⁹ orR¹⁰ is alkyl having 1 to 12 carbons or alkenyl having 2 to 12 carbonsfor decreasing the minimum temperature or decreasing the viscosity.Further preferred R⁴, R⁸ or R¹⁰ is alkoxy having 1 to 12 carbons forincreasing the absolute value of dielectric anisotropy. Preferred R⁵ orR⁶ is alkenyl having 2 to 12 carbons for decreasing the minimumtemperature or decreasing the viscosity, and alkyl having 1 to 12carbons for increasing the stability to ultraviolet light or heat.

Preferred alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. Further preferred alkyl is ethyl, propyl, butyl, pentyl orheptyl for decreasing the viscosity.

Preferred alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. Further preferred alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Preferred alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. Furtherpreferred alkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl fordecreasing the viscosity. A preferred configuration of —CH═CH— in thealkenyl depends on a position of a double bond. Trans is preferred inthe alkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl,3-pentenyl and 3-hexenyl for decreasing the viscosity, for instance. Cis preferred in the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl.In the alkenyl, straight-chain alkenyl is preferred to branched-chainalkenyl.

Preferred examples of alkenyl in which at least one of hydrogen isreplaced by halogen include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. Further preferred examples include2,2-difluorovinyl and 4,4-difluoro-3-butenyl for decreasing theviscosity.

Alkyl does not include cyclic alkyl. Alkoxy does not include cyclicalkoxy. Alkenyl does not include cyclic alkenyl.

Then, m is 1 or 2. Preferred m is 2 for increasing the maximumtemperature, and 1 for decreasing the viscosity.

Then, n is 0, 1 or 2. Preferred n is 2 for increasing the maximumtemperature and 0 for decreasing the viscosity. Further preferred n is 0for decreasing the viscosity.

Then, p is 1, 2 or 3, q is 0 or 1, and a sum of p and q is 1, 2 or 3.Preferred p is 1 or 2 for decreasing the viscosity. Preferred q is 1 forincreasing the optical anisotropy, and 0 for decreasing the viscosity.

Moreover, r is 0, 1 or 2, s is 0 or 1, and a sum of r and s is 1 or 2.Preferred r is 2 for increasing the maximum temperature, and 1 fordecreasing the viscosity. Preferred s is 1 for increasing the maximumtemperature, and 0 for decreasing the minimum temperature.

Ring A is independently:

and in the rings, at least one of ring A is:

two of ring A when m is 2 may be identical or different. Preferred ringA is:

for increasing the absolute value of dielectric anisotropy, and1,4-phenylene for increasing the optical anisotropy.

Ring B, ring C and ring D are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene, andwhen n is 0, at least one of ring C and ring D is 1,4-cyclohexylene, andtwo of arbitrary ring B when n is 2 may be identical or different.Preferred ring B, ring C or ring D is 1,4-cyclohexylene for increasingthe maximum temperature, and 1,4-phenylene for increasing the opticalanisotropy.

Ring E and ring F are independently 1,4-cyclohexylene or 1,4-phenylene,and two of arbitrary ring E when p is 2 or 3 may be identical ordifferent. Preferred ring E or ring F is 1,4-cyclohexylene forincreasing the maximum temperature, and 1,4-phenylene for increasing theoptical anisotropy.

Ring G and ring I are independently 1,4-cyclohexylene or 1,4-phenylene,and two of ring G when r is 2 may be identical or different. Preferredring G or ring I is 1,4-cyclohexylene for increasing the maximumtemperature, and 1,4-phenylene for decreasing the minimum temperature.

With regard to a configuration of 1,4-cyclohexylene, trans is preferredto cis for increasing the maximum temperature.

X¹ and X² are independently fluorine or chlorine. Preferred X¹ or X² isfluorine for decreasing the viscosity.

Y¹ is hydrogen or methyl. Preferred Y¹ is hydrogen for decreasing theviscosity, and methyl for increasing the stability to ultraviolet lightor heat.

Z¹ is independently a single bond, ethylene or methyleneoxy, two ofarbitrary Z¹ when m is 2 may be identical or different. Preferred Z¹ isa single bond or ethylene for decreasing the viscosity, and methyleneoxyfor increasing the absolute value of dielectric anisotropy.

Z² and Z³ are independently a single bond, ethylene, methyleneoxy orcarbonyloxy, two of arbitrary Z² when n is 2 may be identical ordifferent. Preferred Z² or Z³ is a single bond for decreasing theviscosity, and methyleneoxy or carbonyloxy for increasing the dielectricanisotropy.

Z⁴ and Z⁵ are independently a single bond, ethylene or methyleneoxy, andtwo of Z⁴ when p is 2 or 3 may be identical or different. Preferred Z⁴or Z⁵ is a single bond or ethylene for decreasing the viscosity, andmethyleneoxy for increasing the dielectric anisotropy.

Z⁶ and Z⁷ are independently a single bond, ethylene, methyleneoxy orcarbonyloxy, and two of arbitrary Z⁶ when r is 2 may be identical ordifferent. Preferred Z⁶ or Z⁷ is a single bond for decreasing theviscosity, and methyleneoxy or carbonyloxy for increasing the dielectricanisotropy.

Fifth, the specific examples of the component compounds will be shown.

In preferred compounds as described below, R¹¹ and R¹² are independentlystraight-chain alkyl having 1 to 7 carbons, R¹³ is straight-chain alkylhaving 1 to 12 carbons or straight-chain alkenyl having 2 to 12 carbons,R¹⁴ is straight-chain alkyl having 1 to 12 carbons, straight-chainalkoxy having 1 to 12 carbons or straight-chain alkenyl having 2 to 12carbons.

Preferred compound (1) includes compound (1-1). Preferred compound (2)includes compound (2-1-1) to compound (2-8-1). Further preferredcompound (2) includes compound (2-3-1) from compound (2-8-1).Particularly preferred compound (2) includes compound (2-3-1), compound(2-4-1) and compound (2-8-1). Preferred compound (3) includes compound(3-1-1) to compound (3-12-1). Further preferred compound (3) includescompound (3-1-1), and compound (3-4-1) to compound (3-12-1).Particularly preferred compound (3) includes compound (3-1-1), compound(3-6-1), compound (3-7-1) and compound (3-12-1). Preferred compound (4)includes compound (4-1-1) to compound (4-9-1). Further preferredcompound (4) includes compound (4-1-1) to compound (4-7-1). Particularlypreferred compound (4) includes compound (4-1-1), compound (4-3-1),compound (4-4-1), compound (4-6-1) and compound (4-7-1). Preferredcompound (5) includes compound (5-1-1) to compound (5-5-1). Furtherpreferred compound (5) includes compound (5-4-1).

Sixth, the additive that may be mixed with the composition will beexplained. Such an additive includes the optically active compound, theantioxidant, the ultraviolet light absorber, the dye, the antifoamingagent, the polymerizable compound and the polymerization initiator. Theoptically active compound is mixed with the composition for the purposeof inducing a helical structure in liquid crystals to give a twistangle. Examples of such a compound include compound (6-1) to compound(6-4). A preferred ratio of the optically active compound is about 5% byweight or less. A further preferred ratio is in the range of about 0.01%by weight to about 2% by weight.

The antioxidant is mixed with the composition for the purpose ofpreventing a decrease in the specific resistance as caused by heating inair, or maintaining a large voltage holding ratio at room temperatureand also at a temperature close to the maximum temperature of thenematic phase after the device has been used for a long period of time.

Preferred examples of the antioxidant include compound (7) where w is aninteger from 1 to 9. In compound (7), preferred w is 1, 3, 5, 7 or 9.Further preferred w is 1 or 7. Compound (7) where w is 1 is effective inpreventing a decrease in the specific resistance as caused by heating inair because the compound (7) has a large volatility. Compound (7) wherew is 7 is effective in maintaining a large voltage holding ratio at roomtemperature and also at a temperature close to the maximum temperatureof the nematic phase even after the device has been used for a longperiod of time because the compound (7) has a small volatility. Apreferred ratio of the antioxidant is about 50 ppm or more for achievingthe effect thereof, and about 600 ppm or less for avoiding a decrease inthe maximum temperature or avoiding an increase in the minimumtemperature. A further preferred ratio is in the range of about 100 ppmto about 300 ppm.

Preferred examples of the ultraviolet light absorber include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as an amine having steric hindranceis also preferred. A preferred ratio of the ultraviolet light absorberor the stabilizer is about 50 ppm or more for achieving the effectthereof, and about 10,000 ppm or less for avoiding a decrease in themaximum temperature or avoiding an increase in the minimum temperature.A further preferred ratio is in the range of about 100 ppm to about10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition to be adapted for a device having a guest host (GH)mode. A preferred ratio of the dye is in the range of about 0.01% byweight to about 10% by weight. The antifoaming agent such as dimethylsilicone oil or methyl phenyl silicone oil is mixed with the compositionfor preventing foam formation. A preferred ratio of the antifoamingagent is about 1 ppm or more for achieving the effect thereof, and about1,000 ppm or less for avoiding a poor display. A further preferred ratiois in the range of about 1 ppm to about 500 ppm.

The polymerizable compound is mixed with the composition to be adaptedfor the device having the polymer sustained alignment (PSA) mode.Preferred examples of the polymerizable compound include a compoundhaving a polymerizable group, such as an acrylate, a methacrylate, avinyl compound, a vinyloxy compound, a propenyl ether, an epoxy compound(oxirane, oxetane) and a vinyl ketone. Particularly preferred examplesinclude an acrylate derivative or a methacrylate derivative. A preferredratio of the polymerizable compound is about 0.05% by weight or more forachieving the effect thereof, and about 10% by weight or less foravoiding a poor display. A further preferred ratio is in the range ofabout 0.1% by weight to about 2% by weight. The polymerizable compoundis preferably polymerized by irradiation with ultraviolet light or thelike in the presence of a suitable initiator such as aphotopolymerization initiator. Suitable conditions for polymerization,suitable types of the initiator and suitable amounts thereof are knownto a person skilled in the art and are described in literatures. Forexample, Irgacure 651 (registered tradename; BASF), Irgacure 184(registered tradename; BASF) or Darocure 1173 (registered tradename;BASF), each being a photoinitiator, is suitable for radicalpolymerization. A preferred ratio of the photopolymerization initiatoris in the range of about 0.1% by weight to about 5% by weight of thepolymerizable compound, and a particularly preferred ratio is in therange of about 1% by weight to about 3% by weight.

Seventh, the methods for synthesizing the component compounds will beexplained. The compounds can be prepared according to known methods.Examples of synthetic methods will be shown. Compound (1-1) is preparedby the method described in JP S52-53783 A. Compound (2-4-1) is preparedby the method described in JP 2000-008040 A. Compound (3-1-1) isprepared by the method described in JP S59-70624 A. Compound (4-1-1) andcompound (4-4-1) are prepared by the method described in JP H2-503441 A.Compound (4-7-1) is prepared by the method described in JP S57-114532 A.Compound (5-4-1) is prepared by the method described in JP 2005-290349A. The antioxidant is commercially available. A compound represented byformula (7) where w is 1 is available from Sigma-Aldrich Corporation.Compound (7) where w is 7 and so forth are prepared according to themethod described in U.S. Pat. No. 3,660,505 B.

Any compounds whose synthetic methods are not described above can beprepared according to the methods described in books such as OrganicSyntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley &Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press) and NewExperimental Chemistry Course (Shin Jikken Kagaku Koza in Japanese)(Maruzen Co., Ltd.). The composition is prepared according to publiclyknown methods using the thus obtained compounds. For example, thecomponent compounds are mixed and dissolved in each other by heating.

Last, the application of the composition will be explained. Most of thecompositions of the invention mainly have a minimum temperature of about−10° C. or lower, a maximum temperature of about 70° C. or higher, andan optical anisotropy in the range of about 0.07 to about 0.20. Thedevice including the composition has a large voltage holding ratio. Thecomposition is suitable for use in the AM device. The composition isparticularly suitable for use in a transmissive AM device. A compositionhaving an optical anisotropy in the range of about 0.08 to about 0.25may be prepared by controlling the ratio of the component compounds orby mixing with any other liquid crystal compound. The composition can beused as the composition having the nematic phase and as the opticallyactive composition by adding the optically active compound.

The composition can be used for the AM device. The composition can alsobe used for a PM device. The composition can be used for an AM deviceand a PM device both having a mode such as PC, TN, STN, ECB, OCB, IPS,FFS, VA or PSA. Use for the AM device having the IPS, FFS or VA mode isparticularly preferred. The devices may be of a reflective type, atransmissive type or a transflective type. Use for the transmissivedevice is preferred. The composition can also be used for an amorphoussilicon-TFT device or a polycrystal silicon-TFT device. The compositioncan also be used for a nematic curvilinear aligned phase (NCAP) deviceprepared by microencapsulating the composition, and for a polymerdispersed (PD) device in which a three-dimensional network-polymer isformed in the composition.

EXAMPLES

In order to evaluate a composition and a compound to be contained in thecomposition, the composition and the compound were made a measurementobject. When the measurement object was the composition, the compositionwas measured as was, and values obtained were described. When themeasurement object was the compound, a sample for measurement wasprepared by mixing the compound (15% by weight) with mother liquidcrystals (85% by weight). Values of characteristics of the compound werecalculated using values obtained by measurement, according to anextrapolation method: (extrapolated value)={(measured value of asample)−0.85×(measured value of mother liquid crystals)}/0.15. When asmectic phase (or crystals) precipitated at the ratio thereof at 25° C.,a ratio of the compound to the mother liquid crystals was changed stepby step in the order of (10% by weight: 90% by weight), (5% by weight:95% by weight) and (1% by weight: 99% by weight). Values of a maximumtemperature, an optical anisotropy, viscosity and a dielectricanisotropy with regard to the compound were obtained according to theextrapolation method.

Components of the mother liquid crystals and the ratio thereof were asdescribed below.

Physical properties were measured according to the methods describedbelow. Most of the methods were applied as described in a Standard ofthe Japan Electronics and Information Technology Industries Association(hereafter abbreviated as JEITA) (JEITA ED-2521B) as discussed andestablished in JEITA, or as modified thereon.

Maximum Temperature of a Nematic Phase (NI; ° C.):

A sample was placed on a hot plate in a melting point apparatus equippedwith a polarizing microscope and was heated at a rate of 1° C. perminute. Temperature when part of the sample began to change from thenematic phase to the isotropic liquid was measured. A maximumtemperature of the nematic phase may be occasionally abbreviated as“maximum temperature.”

Minimum Temperature of a Nematic Phase (T_(c); ° C.):

Samples each having a nematic phase were put in glass vials and kept infreezers at 0° C., −10° C., −20° C., −30° C. and −40° C. for 10 days,and then liquid crystal phases were observed. For example, when thesample maintained the nematic phase at −20° C. and changed to thecrystals or the smectic phase at −30° C., T_(c) was expressed as“T_(c)≦−20° C.” A minimum temperature of the nematic phase may beoccasionally abbreviated as “minimum temperature.”

Viscosity (Bulk Viscosity; η; Measured at 20° C.; mPa·s):

A cone-plate (E type) rotational viscometer was used for measurement.

Optical Anisotropy (Refractive Index Anisotropy; Δn; Measured at 25°C.):

Measurement was carried out by means of an Abbe refractometer with apolarizing plate mounted on an ocular, using light at a wavelength of589 nanometers. A surface of a main prism was rubbed in one direction,and then a sample was added dropwise onto the main prism. A refractiveindex (n∥) was measured when the direction of polarized light wasparallel to the direction of rubbing. A refractive index (n⊥) wasmeasured when the direction of polarized light was perpendicular to thedirection of rubbing. A value of optical anisotropy was calculated froman equation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δ∈; measured at 25° C.):

A value of dielectric anisotropy was calculated from an equation:Δ∈=∈∥−∈⊥. Dielectric constants (∈∥ and ∈⊥) were measured as describedbelow.

(1) Measurement of dielectric constant (Δ∥): An ethanol (20 mL) solutionof octadecyl triethoxysilane (0.16 mL) was applied onto a well-washedglass substrate. After rotating the glass substrate with a spinner, theglass substrate was heated at 150° C. for 1 hour. A sample was put in aVA device in which a distance (cell gap) between two glass substrateswas 4 micrometers, and the device was sealed with an ultraviolet-curableadhesive. Sine waves (0.5 V, 1 kHz) were applied to the device, andafter 2 seconds, a dielectric constant (∈∥) in the major axis directionof liquid crystal molecules was measured.

(2) Measurement of dielectric constant (∈⊥): A polyimide solution wasapplied onto a well-washed glass substrate. After calcining the glasssubstrate, rubbing treatment was applied to the alignment film obtained.A sample was put in a TN device in which a distance (cell gap) betweentwo glass substrates was 9 micrometers and a twist angle was 80 degrees.Sine waves (0.5 V, 1 kHz) were applied to the device, and after 2seconds, a dielectric constant (∈⊥) in the minor axis direction of theliquid crystal molecules was measured.

Threshold Voltage (Vth; Measured at 25° C.; V):

An LCD-5100 luminance meter made by Otsuka Electronics Co., Ltd. wasused for measurement. A light source was a halogen lamp. A sample wasput in a normally black mode VA device in which a distance (cell gap)between two glass substrates was 4 micrometers and a rubbing directionwas anti-parallel, and the device was sealed with an ultraviolet-curableadhesive. A voltage (60 Hz, rectangular waves) to be applied to thedevice was stepwise increased from 0 V to 20 V at an increment of 0.02V. On the occasion, the device was irradiated with light from adirection perpendicular to the device, and the amount of lighttransmitted through the device was measured. A voltage-transmittancecurve was prepared, in which the maximum amount of light corresponds to100% transmittance and the minimum amount of light corresponds to 0%transmittance. A threshold voltage is a voltage at 10% transmittance.

Voltage Holding Ratio (VHR-1; at 25° C.; %):

A TN device used for measurement had a polyimide alignment film, and adistance (cell gap) between two glass substrates was 5 micrometers. Asample was put in the device, and then the device was sealed with anultraviolet-polymerizable adhesive. A pulse voltage (60 microseconds at5 V) was applied to the TN device and the device was charged. A decayingvoltage was measured for 16.7 milliseconds with a high-speed voltmeter,and area A between a voltage curve and a horizontal axis in a unit cyclewas determined. Area B is an area without decay. A voltage holding ratiois a percentage of area A to area B.

Voltage Holding Ratio (VHR-2; at 80° C.; %):

A TN device used for measurement had a polyimide alignment film, and adistance (cell gap) between two glass substrates was 5 micrometers. Asample was put in the device, and then the device was sealed with anultraviolet-polymerizable adhesive. A pulse voltage (60 microseconds at5 V) was applied to the TN device and the device was charged. A decayingvoltage was measured for 16.7 milliseconds with a high-speed voltmeter,and area A between a voltage curve and a horizontal axis in a unit cyclewas determined. Area B is an area without decay. A voltage holding ratiois a percentage of area A to area B.

Voltage Holding Ratio (VHR-3; at 25° C.; %):

Stability to ultraviolet light was evaluated by measuring a voltageholding ratio after a device was irradiated with ultraviolet light. A TNdevice used for measurement had a polyimide alignment film, and a cellgap was 5 micrometers. A sample was injected into the device, and thenthe device was irradiated with light for 20 minutes. A light source wasan ultra high-pressure mercury lamp USH-500D (made by Ushio, Inc.), anda distance between the device and the light source was 20 centimeters.In measurement of VHR-3, a decaying voltage was measured for 16.7milliseconds. A composition having a large VHR-3 has a large stabilityto ultraviolet light. A value of VHR-3 is preferably 90% or more,further preferably, 95% or more.

Voltage Holding Ratio (VHR-4; at 25° C.; %):

A TN device into which a sample was injected was heated in aconstant-temperature bath at 80° C. for 500 hours, and then stability toheat was evaluated by measuring a voltage holding ratio. In measurementof VHR-4, a decaying voltage was measured for 16.7 milliseconds. Acomposition having a large VHR-4 has a large stability to heat.

Response Time (t; Measured at 25° C.; ms):

An LCD-5100 luminance meter made by Otsuka Electronics Co., Ltd. wasused for measurement. A light source was a halogen lamp. A low-passfilter was set at 5 kHz. A sample was put in a normally black mode VAdevice in which a distance (cell gap) between two glass substrates was 4micrometers and a rubbing direction was anti-parallel, and the devicewas sealed with an ultraviolet-curable adhesive. Rectangular waves (60Hz, 10 V, 0.5 second) were applied to the device. On the occasion, thedevice was irradiated with light from a direction perpendicular to thedevice, and the amount of light transmitted through the device wasmeasured. The maximum amount of light corresponds to 100% transmittance,and the minimum amount of light corresponds to 0% transmittance. Aresponse time is a period of time required for a change from 90%transmittance to 10% transmittance (fall time; millisecond).

Specific Resistance (ρ; measured at 25° C.; Ωcm):

Into a vessel equipped with electrodes, 1.0 milliliter of a sample wasinjected. A DC voltage (10 V) was applied to the vessel, and a DCcurrent after 10 seconds was measured. A specific resistance wascalculated from the following equation: (specificresistance)={(voltage)×(electric capacity of a vessel)}/{(directcurrent)×(dielectric constant of vacuum)}.

Gas Chromatographic Analysis:

GC-14B Gas Chromatograph made by Shimadzu Corporation was used formeasurement. A carrier gas was helium (2 mL per minute). A sampleinjector and a detector (FID) were set to 280° C. and 300° C.,respectively. A capillary column DB-1 (length 30 m, bore 0.32 mm, filmthickness 0.25 μm; dimethylpolysiloxane as a stationary liquid phase,non-polar) made by Agilent Technologies, Inc. was used for separation ofcomponent compounds. After the column was kept at 200° C. for 2 minutes,the column was heated to 280° C. at a rate of 5° C. per minute. A samplewas prepared in an acetone solution (0.1% by weight), and then 1microliter of the solution was injected into the sample injector. Arecorder was C—R5A Chromatopac made by Shimadzu Corporation or theequivalent thereof. The resulting chromatogram showed a retention timeof a peak and a peak area corresponding to each of the componentcompounds.

As a solvent for diluting the sample, chloroform, hexane and so forthmay also be used. The following capillary columns may also be used forseparating the component compounds: HP-1 (length 30 m, bore 0.32 mm,film thickness 0.25 μm) made by Agilent Technologies, Inc., Rtx-1(length 30 m, bore 0.32 mm, film thickness 0.25 μm) made by RestekCorporation and BP-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm)made by SGE International Pty. Ltd. A capillary column CBP1-M50-025(length 50 m, bore 0.25 mm, film thickness 0.25 μm) made by ShimadzuCorporation may also be used for the purpose of avoiding an overlap ofpeaks of the compounds.

A ratio of liquid crystal compounds contained in the composition may becalculated by the method as described below. The liquid crystalcompounds can be detected by means of a gas chromatograph. A ratio ofthe peak areas in the gas chromatogram corresponds to a ratio (in thenumber of moles) of the liquid crystal compounds. When the capillarycolumns described above were used, a correction coefficient of each ofthe liquid crystal compounds may be regarded as 1 (one). Accordingly, aratio (% by weight) of the liquid crystal compounds was calculated fromthe ratio of the peak areas.

The invention will be explained in detail by way of Examples. Theinvention is not limited by the Examples described below. The compoundsin Comparative Examples and Examples were described using symbolsaccording to definitions in Table 3 below. In Table 3, a configurationof 1,4-cyclohexylene is trans. A parenthesized number next to asymbolized compound corresponds to the number of the compound. A symbol(−) means any other liquid crystal compound. A ratio (percentage) of theliquid crystal compounds is expressed in terms of weight percent (% byweight) based on the total weight of the liquid crystal composition. Theliquid crystal composition contains an impurity. Last, values ofcharacteristics of the composition were summarized.

TABLE 3 Method for Description of Compounds using SymbolsR—(A₁)—Z₁- - - -Z_(n)—(A_(n))—R′ 1) Left-terminal Group R— SymbolC_(n)H_(2n+1)— n- C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn-CH₂═CH— V— C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn-C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn- CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)—VFFn- 2) Right-terminal Group —R′ Symbol —C_(n)H_(2n+1) -n—OC_(n)H_(2n+1) —On —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1) —Vn—C_(n)H_(2n)—CH═CH₂ -nV —CH═CF₂ —VFF —OC_(n)H_(2n)—CH═CH₂ —OnV 3)Bonding Group —Z_(n)— Symbol —OC_(n)H_(2n)O— OnO —C_(n)H_(2n)— n —COO— E—CH═CH— V —CH₂O— 1O —OCH₂— O1 —SiH₂— Si 4) Ring Structure —A_(n)— Symbol

H

Ch

B

B(2F)

B(2CL)

B(F)

B(2F,3F)

B(2F,3CL)

B(2CL,3F)

B(3F,6F)

B(2F,3F,6Me)

dh

Dh

Cro(7F,8F) 5) Example of Description Example 1 1-BB-3

Example 2 3-HHB(2F,3F)-O2

Example 3 5-HBB(F)B-3

Example 4 3-HHB(2F,3F)-O2

Comparative Example 1

Example 7 was selected from Examples disclosed in JP 2009-270026 A. Thereason is that the composition includes compound (1), compound (3) andcompound (4). Components and characteristics of the composition are asdescribed below.

1-BB-5 (1-1) 3% 3-HH—V (3-1-1) 25% 3-HH—V1 (3-1-1) 7% V2—BB (F) B-3(3-6-1) 3% 3-HBBH-5 (3-9-1) 3% 5-HBB (F) B-3 (3-12-1) 6% V—HB (2F,3F)—O2 (4-1-1) 10% V—HB (2F, 3F)—O4 (4-1-1) 10% 5-BB (2F, 3F)—O2 (4-3-1)5% 3-HBB (2F, 3F)—O2 (4-7-1) 10% 5-HBB (2F, 3F)—O2 (4-7-1) 9% 3-H1OB(2F, 3F) B (2F, 3F)—O4 (-) 3% 5-H1OB (2F, 3F) B (2F, 3F)—O4 (-) 3%5-HH1OB (2F, 3F) B (2F, 3F)—O4 (-) 3%

NI=82.2° C.; Tc≦−20° C.; Δn=0.113; η=25.7 mPa·s; Δ∈=−2.9; Vth=2.31 V.

Example 1

In the composition in Comparative Example 1, component compounds that donot correspond to a first component to a fifth component according tothe present application were replaced by compound (2-4-1). The presentcomposition was prepared and measurement was carried out by the methodsdescribed above. Components and characteristics of the composition areas described below. In Example 1, viscosity is smaller and an absolutevalue of dielectric anisotropy is larger, as compared with ComparativeExample 1.

1-BB-5 (1-1) 3% 3-HH—V (3-1-1) 25% 3-HH—V1 (3-1-1) 7% V2—BB (F) B-3(3-6-1) 3% 3-HBBH-5 (3-9-1) 3% 5-HBB (F) B-3 (3-12-1) 6% V—HB (2F,3F)—O2 (4-1-1) 10% V—HB (2F, 3F)—O4 (4-1-1) 10% 5-BB (2F, 3F)—O2 (4-3-1)5% 3-HBB (2F, 3F)—O2 (4-7-1) 10% 5-HBB (2F, 3F)—O2 (4-7-1) 9% 3-HDhB(2F, 3F)—O2 (2-4-1) 9%

NI=82.3° C.; Tc≦−20° C.; Δn=0.109; η=18.8 mPa·s; Δ∈=−3.1; VHR-1=98.9%;VHR-2=97.8%; VHR-3=97.9%.

Comparative Example 2

Example 5 was selected from Examples disclosed in JP 2008-19425

A. The reason is that the composition includes a compound similar tocompound (1), compound (3) and compound (4). Components andcharacteristics of the composition are as described below.

3-BB—O2 Similar to (1) 13% 5-BB—O2 Similar to (1) 5% 2-BB (F) B-3(3-6-1) 5% 5-HBB (F) B-2 (3-12-1) 4% 5-HBB (F) B-3 (3-12-1) 4% 3-H2B(2F, 3F)—O2 (4-2-1) 14% 3-H2B (2F, 3F)—O4 (4-2-1) 7% 5-H2B (2F, 3F)—O2(4-2-1) 14% 3-HH2B (2F, 3F)—O2 (4-5-1) 10% 4-HH2B (2F, 3F)—O2 (4-5-1) 6%5-HH2B (2F, 3F)—O2 (4-5-1) 6% 3-HBB (2F, 3F)—O2 (4-7-1) 8% 5-HBB (2F,3F)—O2 (4-7-1) 4%

NI=83.0° C.; Tc≦−20° C.; Δn=0.127; η=28.3 mPa·s; Δ∈=−2.8; Vth=2.57 V.

Comparative Example 3

Example M8 was selected from the compositions disclosed in JP2008-505235 A. The reason is that the composition includes compound (1),compound (3) and compound (4). The present composition was prepared, andmeasurement was carried out by the methods described above. Componentsand characteristics of the composition are as described below.

1-BB-4 (1-1) 7% 3-HH—V1 (3-1-1) 12% V—HHB-1 (3-4-1) 10% 3-HBB-2 (3-5-1)10% 3-BB (2F, 3F)—O2 (4-3-1) 19% 5-BB (2F, 3F)—O2 (4-3-1) 17% 2-HBB (2F,3F)—O2 (4-7-1) 12% 3-HBB (2F, 3F)—O2 (4-7-1) 13%

NI=72.3° C.; Tc≦−10° C.; Δn=0.147; η=20.3 mPa·s; Δ∈=−3.4.

Example 2

1-BB-1 (1-1) 5% 1-BB-3 (1-1) 5% 3-BB-5 (1-1) 5% 3-DhHB (2F, 3F)—O2(2-3-1) 3% V—DhHB (2F, 3F)—O2 (2-3-1) 3% 3-HDhB (2F, 3F)—O2 (2-4-1) 7%V2—HDhB (2F, 3F)—O2 (2-4-1) 3% 1V2—HDhB (2F, 3F)—O2 (2-4-1) 3% V—DhH1OB(2F, 3F)—O2 (2-6-1) 4% 3-DhH1OB (2F, 3F)—O2 (2-6-1) 6% 5-DhH1OB (2F,3F)—O2 (2-6-1) 5% 3-dhBB (2F, 3F)—O2 (2-8-1) 5% 5-DhB (2F, 3F)—O2 (2) 5%3-HH—V (3-1-1) 23% 3-HH—V1 (3-1-1) 8% 2-HH—2V1 (3-1-1) 3% 3-HHEBH-3(3-8-1) 3% 3-HHEBH-5 (3-8-1) 4%

NI=83.8° C.; Tc≦−20° C.; Δn=0.096; η=19.1 mPa·s; Δ∈=−3.4; VHR-1=99.6%;VHR-2=98.1%; VHR-3=97.9%.

Example 3

1-BB-1 (1-1) 3% 1-BB-3 (1-1) 7% 3-DhHB (2F, 3F)—O2 (2-3-1) 5% 2-HDhB(2F, 3F)—O2 (2-4-1) 6% 3-HDhB (2F, 3F)—O2 (2-4-1) 7% V—DhH1OB (2F,3F)—O2 (2-6-1) 3% 3-DhH1OB (2F, 3F)—O2 (2-6-1) 7% 5-DhH1OB (2F, 3F)—O2(2-6-1) 6% 3-DhB (2F, 3F)—O2 (2) 6% 3-HH-5 (3-1-1) 5% 3-HH—V (3-1-1) 30%3-HH—V1 (3-1-1) 6% 3-HHEBH-3 (3-8-1) 6% 3-HHEBH-5 (3-8-1) 3%

NI=84.3° C.; Tc≦−20° C.; Δn=0.084; η=18.4 mPa·s; Δ∈=−3.4; VHR-1=99.5%;VHR-2=98.3%; VHR-3=98.1%.

Example 4

1-BB-3 (1-1) 5% 2-BB-3 (1-1) 5% 3-DhHB (2F, 3F)—O2 (2-3-1) 5% 2-HDhB(2F, 3F)—O2 (2-4-1) 3% 3-HDhB (2F, 3F)—O2 (2-4-1) 7% V—DhH1OB (2F,3F)—O2 (2-6-1) 3% 3-DhH1OB (2F, 3F)—O2 (2-6-1) 7% 5-DhH1OB (2F, 3F)—O2(2-6-1) 6% 5-DhB (2F, 3F)—O2 (2) 9% 3-HH—V (3-1-1) 30% 3-HH—V1 (3-1-1)8% 3-HHEH-5 (3-3-1) 3% 3-HHEBH-3 (3-8-1) 6% 3-HHEBH-5 (3-8-1) 3%

NI=83.2° C.; Tc≦−20° C.; Δn=0.082; η=18.9 mPa·s; Δ∈=−3.5; VHR-1=99.4%;VHR-2=97.8%; VHR-3=98.1%.

Example 5

1-BB-5 (1-1) 5% 3-dhB (2F, 3F)—O2 (2-1-1) 3% 5-Dh2B (2F, 3F)—O2 (2-2-1)3% 5-DhH2B (2F, 3F)—O2 (2-5-1) 5% 3-HH-5 (3-1-1) 3% 3-HH—O1 (3-1-1) 3%3-HH—V1 (3-1-1) 8% 3-HH—VFF (3-1) 10% 3-HB—O1 (3-2-1) 7% 5-HB (F) HH—V(3-10-1) 3% 5-HB (F) HH—V1 (3-10-1) 3% 5-HB (F) BH-5 (3-11-1) 5% 3-HB(2F, 3F)—O2 (4-1-1) 8% 3-H2B (2F, 3F)—O4 (4-2-1) 8% 3-HHB (2F, 3F)-1(4-4-1) 5% 3-HH2B (2F, 3F)—O2 (4-5-1) 8% 3-HH1OB (2F, 3F)—O2 (4-6-1) 5%5-HH1OB (2F, 3F)—O2 (4-6-1) 8%

NI=85.3° C.; Tc≦−20° C.; Δn=0.093; η=18.5 mPa·s; Δ∈=−3.4; VHR-1=99.6%;VHR-2=98.1%; VHR-3=98.1%.

Example 6

1-BB-1 (1-1) 5% 1-BB-5 (1-1) 5% 2-BB-3 (1-1) 5% 3-BB-5 (1-1) 5% 5-DhBB(2F, 3F)—O2 (2-7-1) 3% 5-DhB (2F, 3F)—O2 (2) 3% 3-HH—V (3-1-1) 6%3-HH—V1 (3-1-1) 5% 3-HH—VFF (3-1) 5% 3-HHB—O1 (3-4-1) 3% 3-HBB-2 (3-5-1)5% 5-B (F) BB-3 (3-7-1) 3% 5-HBB (F) B-3 (3-12-1) 3% 5-BB (2F, 3F)—O2(4-3-1) 5% V2—BB (2F, 3F)—O2 (4-3-1) 5% 1V2—BB (2F, 3F)—O2 (4-3-1) 3%5-HH2B (2F, 3F)—O2 (4-5-1) 5% 3-HH1OB (2F, 3F)—O2 (4-6-1) 7% 5-HH1OB(2F, 3F)—O2 (4-6-1) 8% 5-HBB (2F, 3F)—O2 (4-7-1) 5% 3-HHB (2F, 3CL)—O2(4-8-1) 3% 2-BB (2F, 3F) B-4 (4-9-1) 3%

NI=83.9° C.; Tc≦−20° C.; Δn=0.135; η=18.7 mPa·s; Δ∈=−3.5; VHR-1=99.1%;VHR-2=98.1%; VHR-3=98.2%.

Example 7

1-BB-3 (1-1) 5% 3-BB-5 (1-1) 5% 3-HDhB (2F, 3F)—O2 (2-4-1) 5% 3-HH—V(3-1-1) 20% 3-HH—V1 (3-1-1) 7% 1-HH—2V1 (3-1-1) 5% 3-HH—2V1 (3-1-1) 5%2-BB (F) B-3 (3-6-1) 3% 3-HHEBH-3 (3-8-1) 5% 5-H2B (2F, 3F)—O2 (4-2-1)10% 5-HHB (2F, 3F)—O2 (4-4-1) 5% 4-HH2B (2F, 3F)—O2 (4-5-1) 5% 5-HH1OB(2F, 3F)—O2 (4-6-1) 8% 5-H2Cro (7F, 8F)-5 (5-1-1) 3% 5-H1OCro (7F, 8F)-5(5-2-1) 3% 3-HH2Cro (7F, 8F)-5 (5-3-1) 3% 5-HH1OCro (7F, 8F)-5 (5-4-1)3%

NI=84.0° C.; Tc≦−20° C.; Δn=0.091; η=18.5 mPa·s; Δ∈=−3.4; VHR-1=98.8%;VHR-2=97.6%; VHR-3=97.8%.

Example 8

1-BB-1 (1-1) 5% 1-BB-5 (1-1) 5% 3-BB-5 (1-1) 3% 2-HDhB (2F, 3F)—O2(2-4-1) 5% 3-HH-5 (3-1-1) 5% 3-HH—V (3-1-1) 11% 3-HH—V1 (3-1-1) 6%1-HH—2V1 (3-1-1) 5% 3-HHEH-5 (3-3-1) 5% V-HHB-1 (3-4-1) 6% 3-H2B (2F,3F)—O4 (4-2-1) 9% 5-H2B (2F, 3F)—O2 (4-2-1) 5% 3-HH2B (2F, 3F)—O2(4-5-1) 5% 3-HH1OB (2F, 3F)—O2 (4-6-1) 3% 5-HH1OB (2F, 3F)—O2 (4-6-1) 5%3-HHB (2CL, 3F)—O2 (4) 3% 5-HB1OCro (7F, 8F)-5 (5-5-1) 3% 4O-Cro (7F,8F) H-3 (5) 3% 3-HH1OB (2F, 3F, 6Me)—O2 (4) 3% 1O1-HBBH-4 (-) 5%

NI=83.4° C.; Tc≦−20° C.; Δn=0.099; η=18.7 mPa·s; Δ∈=−3.3; VHR-1=98.9%;VHR-2=97.7%; VHR-3=97.8%.

Example 9

1-BB-3 (1-1) 6% 1-BB-7 (1-1) 3% 2-BB-3 (1-1) 4% 3-BB-5 (1-1) 5% 3-dhBB(2F, 3F)—O2 (2-8-1) 4% 5-DhB (2F, 3F)—O2 (2) 6% 3-HH—V (3-1-1) 5%3-HH—V1 (3-1-1) 5% 3-HH—VFF (3-1) 5% V2-BB (F) B-3 (3-6-1) 3% 5-B (F)BB-2 (3-7-1) 5% 3-HHEBH-3 (3-8-1) 3% 5-HBB (F) B-2 (3-12-1) 3% 8-BB (2F,3F)—O2 (4-3-1) 5% 1V2—BB (2F, 3F)—O2 (4-3-1) 5% 3-HH2B (2F, 3F)—O2(4-5-1) 5% 3-HH1OB (2F, 3F)—O2 (4-6-1) 8% 4-HH1OB (2F, 3F)—O2 (4-6-1) 4%5-HH1OB (2F, 3F)—O2 (4-6-1) 8% V2—HBB (2F, 3F)—O2 (4-7-1) 4% 1V2—HBB(2F, 3F)—O2 (4-7-1) 4%

NI=86.3° C.; Tc≦−20° C.; Δn=0.131; η=18.8 mPa·s; Δ∈=−3.4; VHR-1=99.1%;VHR-2=98.2%; VHR-3=97.6%.

The compositions in Example 1 to Example 9 have a smaller viscosity anda larger absolute value of dielectric anisotropy, as compared with thecompositions in Comparative Examples 1 and 2, and a higher maximumtemperature and a smaller viscosity, as compared with the composition inComparative Example 3. Thus, the liquid crystal composition according tothe invention is so much superior in characteristics to the compositionsshown in Patent literature Nos. 1 to 4.

INDUSTRIAL APPLICABILITY

The invention concerns a liquid crystal composition satisfying at leastone of characteristics such as a high maximum temperature of a nematicphase, a low minimum temperature of the nematic phase, a smallviscosity, a suitable optical anisotropy, a large negative dielectricanisotropy, a large specific resistance, a high stability to ultravioletlight and a high stability to heat, or a liquid crystal compositionhaving a suitable balance regarding at least two of the characteristics.A liquid crystal display device including such a composition is appliedto constitute an AM device having a short response time, a large voltageholding ratio, a large contrast ratio, a long service life and so forth,and thus can be used for a liquid crystal projector, a liquid crystaltelevision and so forth.

1. A liquid crystal composition that has a negative dielectricanisotropy and contains at least one compound selected from the group ofcompounds represented by formula (1) as a first component and at leastone compound selected from the group of compounds represented by formula(2) as a second component:

wherein R¹ and R² are independently alkyl having 1 to 12 carbons; R³ andR⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; ring A is independently:

and in the rings, at least one of ring A is:

Z¹ is independently a single bond, ethylene or methyleneoxy; and m is 1or
 2. 2. The liquid crystal composition according to claim 1, whereinthe second component is at least one compound selected from the group ofcompounds represented by formula (2-1) to formula (2-8):

wherein R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons. 3-4.(canceled)
 5. The liquid crystal composition according to claim 1,wherein a ratio of the first component is in the range of 5% by weightto 40% by weight, and a ratio of the second component is in the range of5% by weight to 95% by weight, based on the total weight of the liquidcrystal composition.
 6. The liquid crystal composition according toclaim 1, further containing at least one compound selected from thegroup of compounds represented by formula (3) as a third component:

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring B, ring C and ring D are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene; Z² andZ³ are independently a single bond, ethylene, methyleneoxy orcarbonyloxy; and n is 0, 1 or 2, and when n is 0, at least one of ring Cand ring D is 1,4-cyclohexylene.
 7. The liquid crystal compositionaccording to claim 6, wherein the third component is at least onecompound selected from the group of compounds represented by formula(3-1) to formula (3-12):

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenyl having2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine.8-9. (canceled)
 10. The liquid crystal composition according to claim 6,wherein a ratio of the third component is in the range of 10% by weightto 90% by weight based on the total weight of the liquid crystalcomposition.
 11. The liquid crystal composition according to claim 1,further containing at least one compound selected from the group ofcompounds represented by formula (4) as a fourth component:

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons; ring E andring F are independently 1,4-cyclohexylene or 1,4-phenylene; Z⁴ and Z⁵are independently a single bond, ethylene or methyleneoxy; X¹ and X² areindependently fluorine or chlorine; Y¹ is hydrogen or methyl; and p is1, 2 or 3, q is 0 or 1, and a sum of p and q is 1, 2 or
 3. 12. Theliquid crystal composition according to claim 11, wherein the fourthcomponent is at least one compound selected from the group of compoundsrepresented by formula (4-1) to formula (4-9):

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons.
 13. The liquidcrystal composition according to claim 12, wherein the fourth componentis at least one compound selected from the group of compoundsrepresented by formula (4-1).
 14. The liquid crystal compositionaccording to claim 12, wherein the fourth component is at least onecompound selected from the group of compounds represented by formula(4-4).
 15. The liquid crystal composition according to claim 12, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-6).
 16. The liquid crystalcomposition according to claim 11, wherein a ratio of the fourthcomponent is in the range of 5% by weight to 80% by weight based on thetotal weight of the liquid crystal composition.
 17. The liquid crystalcomposition according to claim 1, further containing at least onecompound selected from the group of compounds represented by formula (5)as a fifth component:

wherein R⁹ and R¹⁰ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; ring Gand ring I are independently 1,4-cyclohexylene or 1,4-phenylene; Z⁶ andZ⁷ are independently a single bond, ethylene, methyleneoxy orcarbonyloxy; and r is 0, 1 or 2, s is 0 or 1, and a sum of r and s is 1or
 2. 18. The liquid crystal composition according to claim 17, whereinthe fifth component is at least one compound selected from the group ofcompounds represented by formula (5-1) to formula (5-5):

wherein R⁹ and R¹⁰ are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons. 19.(canceled)
 20. The liquid crystal composition according to claim 17,wherein a ratio of the fifth component is in the range of 5% by weightto 40% by weight based on the total weight of the liquid crystalcomposition.
 21. The liquid crystal composition according to claim 1,wherein a maximum temperature of a nematic phase is 70° C. or higher, anoptical anisotropy (25° C.) at a wavelength of 589 nanometers is 0.08 ormore, and a dielectric anisotropy (25° C.) at a frequency of 1 kHz is −2or less.
 22. A liquid crystal display device, comprising the liquidcrystal composition according to claim
 1. 23. The liquid crystal displaydevice according to claim 22, wherein an operating mode in the liquidcrystal display device is a VA mode, an IPS mode, a FFS mode or a PSAmode, and a driving mode in the liquid crystal display device is anactive matrix mode.
 24. Use of a liquid crystal composition in theliquid crystal display device according to claim 22.